Method of tempering glass sheets



Jan. 7, 1947. B. LONG vMETHOD OF TEMPERING GLASS SHEETS Original Filed-April 2, 1936 DDDDEIDDEIDDDD u n u a n n a n .n a n n u 6 ramas Jan. 7, 1947 METHOD OF TEMPERING GLASS SHEETS Bernard Long, Paris, France; vested in the Alien Property Custodian Original application April 2, 1936, Serial No.

72,411. Divided and this application September 29, 1939, Serial No. 297,183.

April 6, 1935 2 Claims.

In the processes now employed for the tempering of sheets of glass Wherek the cooling is effected by means of a blowingof air or a cooling uid, the products obtained present defects' or visible iridescent spots when the sheets are eX- amined under an oblique incidence, and which, although slight, still are detrimental to the appearance and the commercial value of these sheets. These iridescent spots correspond to the variable effects of the birefringence of glass and are due to the insufficiently regular cooling of the surface of the glass by the blowing members.

The means put into practice up to now in order to attenuate these iridescent spots have consisted in rapidly displacing upon the surface of the glass the zones f impact of the jets of air issuing from several orifices. But the methods which have been used for this purpose .have notgiven completely satisfactory results and iridescent spots are still found upon the tempered products, which are due to variations in the cooling action between certain zones and the adjacent zones and which correspond either to the form of the oriflces or to the trajectory which has been imparted to the latter.

In this application there is disclosed a particular method and apparatus `for the remedying of the above objections. other and different methods and apparatus for the same purpose being disclosed in my prior application, Serial No. 72,411, led April 2, 136, which issuedv as Patent No. 2,303,749, Dec. 1, 1942, and of which this application is a division.

The invention reserved for this application, generally stated, comprehends the heating of a sheet or plate of glass to approximately its softening point and then by suitable means causing the sheet to travel between a plurality of stationary bars or boxes each provided with slits so that the glass is rapidly chilled by the travel of the glass past these slits. The sheet or plate of glass may then be brought to rest between oppositely disposed blow heads from which cooling jets issue,

' wherebythe glass sheet may be further rapidly chilled.

Experience has shown that the sheets of tempered glass obtained by this process of cooling do not present any birefringent defects, whatever the incidence under which they are observed. Moreover, it has been established that it is suflicient to eiect the beginning of the cooling of the In France sheet of glass by this process and that it is possible to stop after the passage of a certain nurnber of the waves oi air and to msh by the aid ol known means, such as, for example, a simple blowing by grilles or plates provided with stationary openings.

Figure 1 is a View illustrating the valve arrangement for carrying out my invention.

Figure 2 is a plan View illustrating the heating oven, stationary boxes for projecting the cooling air upon the sheets in the form of ribbons or bands and also the stationary cooling device.

The sheet l leaving an oven 61 passes between two seriesr of hollow bars E8 having slits and supplied by a cooling fluid under pressure.

1n lorder to avoid unnecessary expense of the fluid it is advisable to supply only those of the bars which are in active position in relation to the sheet. For this purpose it is possible to furnish the carriage carrying thev sheet with an operating plate GS, (Fig. 1), acting upon cams 'lilwhich open or close the cocks placed upon the pipes bringing the i'luid to the bars t8.

In order to attain the complete cooling of the sheet with this apparatus it is necessary to have two .extended rows of bars. However, if this be objectionable it can be avoided by effecting only the beginning of the tempering by the means characterizing the invention and by finishing it by means of apparatus l I'between which the sheet remains stationary. This apparatus of known type may consist simply of xed jets of air effected by means of holes and without movement of the latter,

lWhat I claim is:

l. The method of tempering glass sheets or plates which consists in heating a glass plate to its softening point, and translating the plate endwise past a plurality of continuous strips or sheetsof cooling uid disposed to cross the path of travel of the glass plate.

2. The method of tempering glass sheets or plates which consists in heating a glass plate'to its softening point,translating the plate endwise past a plurality of continuous strips or sheets of cooling uid disposed to cross the path of travel of the glass plate, and thereafter bringing the plate to rest between oppositely disposed jets of:

cooling fluid.

BERNARD LONG. 

